Tie-downs are used to secure many types of loads onto vehicles and other support platforms. For example, flatbed trailers are typically equipped with a series of tie-down assemblies along their length. To secure cargo, a trucker may need to extend a series of flexible straps from one side of the trailer to the other and then manually tighten the straps. As another example, consumers may use portable tie-downs to secure purchases to their personal vehicle, such as to the bed of a pickup truck or roof of a sport-utility vehicle (SUV). Having to manually tighten tie-downs can be physically exhausting and time consuming. Existing powered strap winders and automatic take-up winches are designed to be permanently affixed to commercial vehicles and may be too bulky and inflexible for use in many situations.